简便计算1990+19901990+199019901990 1——————————————— - ——1989+198
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简便计算
1990+19901990+199019901990 1
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1989+19891989+198919891989 1989
1990+19901990+199019901990 1
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1989+19891989+198919891989 1989
![简便计算1990+19901990+199019901990 1——————————————— - ——1989+198](/uploads/image/z/7836557-5-7.jpg?t=%E7%AE%80%E4%BE%BF%E8%AE%A1%E7%AE%971990%2B19901990%2B199019901990+1%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94+-+%E2%80%94%E2%80%941989%2B198)
1990+19901990+199019901990 1
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1989+19891989+198919891989 1989
=[1990*(1+10001+100010001)]/[1989*(1+10001+100010001)]-1/1989
=1990/1989-1/1989
=(1990-1)/1989
=1989/1989
=1
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1989+19891989+198919891989 1989
=[1990*(1+10001+100010001)]/[1989*(1+10001+100010001)]-1/1989
=1990/1989-1/1989
=(1990-1)/1989
=1989/1989
=1